Periodontal disease occurs when bacteria colonize the sulcus space between the teeth and gingiva The bacteria cause inflammation. The inflammation destroys the gingival epithelial lining and epithelial attachment to the tooth. The inflammation then progresses down the tooth root toward the apex of the root and destroys periodontal structure and bone. As periodontal disease progresses open pockets develop between the tooth and the gingiva. A dentist can determine the presence and extent of periodontal disease using a probe to measure the depth of pockets between each tooth and gingiva. X-rays can reveal the extent of any bone loss.
A common surgical procedure has been widely used to treat bone loss caused by periodontal disease. In this procedure the periodontist uses a scalpel to incise the gingiva and reflects it back to expose the tooth root and bone. Then he removes the irregular shaped bone with hand instruments or rotary instruments, surgically removes granulation tissue and gingiva, cleans the site and places a bone regeneration material into osseous defects that remain in the bone. Guided Tissue Regeneration barriers are placed over bone regeneration material in deeper osseous defects. He then sutures the gingiva around the tooth. Then the gingiva, epithelial attachment, bone, and periodontal ligament between the tooth and bone reform. While this procedure has been effective, incisions in the gingiva cause patient discomfort, pain, swelling, gingival recession, sensitive teeth, a long healing time, and increase the possibility of infection. The goal of visualization of the roots, removal of granulation tissue, and excision of damaged gingiva utilizing traditional incision periodontal surgery on a normal compliment of 28 teeth requires a cumulative incision length of 41 to 46 inches. The extensive cumulative length of surgical incisions wears down the scalpel cutting edge. It is common surgical practice to use and discard between 4 to 10 Bard Parker #15 surgical scalpel blades for each patient. To reposition all of the surgically loosened gingiva requires between 4 to 8 suture packets of 18 inch suture. The volume of granulation tissue and gingiva removed is approximately 2 to 5 cc. Estimated blood loss varies 2 cc to 18 cc per patient. The post-surgical period requires strong analgesics to maintain pain relief. At the 2 week suture removal appointment, the gingival incisions are only about 50% healed, and require 2 to 4 additional weeks for final healing. The period of painful, sensitive, and bleeding gingiva lasts 3 to 4 weeks after the surgery. After this struggle to gain periodontal health, the patient now faces gingival recession with exposed sensitive roots resulting from granulation and gingiva removal. Cosmetic difficulties result from the loss of the interdental gingiva that creates dark spaces between the teeth. The exposure of the margins of facings and crowns often requires replacement to correct cosmetic deficiencies.
Consequently, there is also a need for a procedure for reversing bone loss and periodontal structure damage caused by periodontal disease. There is also a need for a regeneration material that could be used without incisions to regenerate bone and periodontal structure lost to periodontal disease. Periodontal therapy without incisions, eliminates discomfort, pain, swelling, gingival recession, sensitive teeth, greatly shortens healing time, and greatly decreases potential for infections.
A variety of materials are available and have been used for bone regeneration. Autogenous bone has long been considered the “gold standard” of bone grafting material. This is bone material taken from other parts of a patient's body. The primary shortcomings in the use of autogenous bone is the need for a second operative site, the attendant patient morbidity and the possibility of being unable to obtain sufficient material. The art has also used bone particles taken from cadavers. These bone particles may be frozen, freeze-dried, demineralized freeze-dried and irradiated. Patients are reluctant to accept cadaver bone because health of the recipient may depend upon the health history of the donor. Consequently, other bone growth materials, not taken from humans, are more frequently used for bone regeneration.
Over the last two decades, ceramics, such as hydroxylapatite and tricalcium phosphate, and polymers have received the most attention as substitutes for autogenous bone grafts. Calcium phosphate ceramics act through osteoconduction by providing a scaffold for enhanced bone tissue repair and growth.
Calcium carbonate is another inorganic material used for bone grafting. It has been reported that a natural coral containing over 98% calcium carbonate and sold under the trademark BioCoral is effective as a bone growth material for periodontal disease. This material is provided as granules 300 microns to 400 microns in diameter.
Another bone graft material is a synthetic bone sold under the trademark Bioplant HJR. This material contains a calcium hydroxide in a co-polymer of polyhydroxyehyl methacrylate and polymethyl-methacrylate. This material is also provided and used in granular form.
It is well known to combine other materials with bone growth materials when used to promote bone growth. Calcium sulfate hemihydrate, also known as medical grade plaster, is often combined with hydroxylapatite to provide initial stabilization and prevent migration to surrounding soft tissues. The calcium sulfate is resorbed by the body within one month leaving a scaffold of hydroxylapatite for bone growth. Chen et al. in U.S. Pat. No. 5,707,962 teach that growth factors, such as collagen, nutrient factors, drugs, anti-microbial agents, calcium containing compounds, blood proteins or products and anti-inflammatory agents may be combined with the matrix or scaffold forming material such as hydroxylapatite. The patent teaches that deminerialized bone particles or powder or Bone Morphogenic Protein or proteins be added to collagen powder or fleece to form a bone sponge. The patent teaches that chips of this sponge or sponge ground into powder or fleece can be used. Collagen in this form is not free to react with body tissue like collagen powder. Chen et al. do not teach how the compositions they disclosed are to be used except for saying they are implanted by standard surgical or dental procedures.
U.S. Pat. No. 5,292,253 describes a procedure in which missing bone is filled with a mass of calcium phosphate or hydroxylapatite and covered with a gel containing a collagen, fibrin or gelatin and a dye. The gel is then exposed to laser radiation to weld the calcium containing material to the bone. This is an expensive treatment and puts the patient at risk of exposure to harmful laser radiation, particularly if the patient moves an eye into the path of the laser.
U.S. Pat. No. 5,352,715 discloses an injectable composition of collagen and mineral materials, such as hydroxyapatite or tricalcium phosphate. The composition also includes a carrier such as polyethylene glycol, hyalurionic acid and poly (hydroxyethyl methactylate) which makes the composition a gel. The gel is injected through a needle. The composition may also include lubricants, such as glycerin, which allow the composition to pass more easily through a needle. That needle has a diameter of 20 gauge or smaller. The organic polymers and any collagen in the composition do not act as a matrix but are absorbed by the body, leaving the ceramic material as the supporting matrix. Although the patent says that the material is an injectable implant composition that can be used for bone repairs, there is no teaching that the material can be used to treat periodontal disease. The patent teaches that any type of collagen can be used. There is also no teaching that the composition change viscosity or harden shortly after injection.
All present periodontal surgery methods require incisions to allow removal of bone, soft tissue, and to allow visual inspection of the root surface. One problem associated with the use of the bone growth materials described above is that the particle sizes require incisions in the gingiva to apply the material. However, in addition to the problems mentioned above, surgical procedures always require more healing time than procedures that do not require incisions. However, the art has not developed a procedure for treating bone loss from periodontal disease that does not require incisions in the gingiva. Consequently, there is a need for a bone growth material that can be placed adjacent to a degenerated alveolar bone to promote bone growth without requiring incisions in the gingiva. There is also a need for a procedure to place such a material to reverse periodontal disease without incisions in a patient's gingiva. Such a procedure and material should not merely grow bone. Rather, they should result in reforming of the epithelial attachment and encourage periodontal structure regeneration.
Any composition that is injected into the periodontal pocket must not migrate out of the pocket after injection. While the injectable gel-type bone growth compositions disclosed in the prior art could be injected into the periodontal pocket, they would migrate out of the pocket before they would have much effect as a result of normal rebound or retraction of the distended pocket and movement of the mouth.